Fuel cell fluid distribution layer having integral sealing capability

ABSTRACT

A fuel cell fluid distribution layer, in one embodiment, comprises perforated graphite foil. The fluid distribution layer can have one or more reactant flow field channels formed in one or both major surfaces, one or more manifold openings, conductive filler on one or both major surfaces, conductive filler at least partially filling some or all perforations and/or an electrocatalyst one or both major surfaces.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.10/037,506, filed on Jan. 4, 2002 now abandoned, entitled “Fuel CellFluid Distribution Layer Having Integral Sealing Capability”. The '506application is, in turn, a continuation of U.S. patent application Ser.No. 09/384,531, filed on Aug. 27, 1999 now U.S. Pat. No. 6,350,538,entitled “Electrochemical Cell With Fluid Distribution Layer HavingIntegral Sealing Capability”. The '531 application is, in turn, acontinuation-in-part of U.S. patent application Ser. No. 09/309,677,filed on May 11, 1999 now abandoned, also entitled “Electrochemical CellWith Fluid Distribution Layer Having Integral Sealing Capability”. The'677 application is, in turn, a continuation of U.S. patent applicationSer. No. 08/846,653, filed on May 1, 1997 now U.S. Pat. No. 5,976,726,also entitled “Electrochemical Cell With Fluid Distribution Layer HavingIntegral Sealing Capability”. Each of the '506, '531 '677 and '653applications is hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

This invention relates to fuel cell fluid distribution layers havingintegral sealing capability.

BACKGROUND OF THE INVENTION

Electrochemical fuel cells convert fuel and oxidant to electricity andreaction product. Solid polymer fuel cells generally employ a membraneelectrode assembly (“MEA”) comprising a solid polymer electrolyte or ionexchange membrane disposed between two fluid distribution (electrodesubstrate) layers formed of electrically conductive sheet material. Thefluid distribution layer has a porous structure across at least aportion of its surface area, which renders it permeable to fluidreactants and products in the fuel cell. The electrochemically activeregion of the MEA also includes a quantity of electrocatalyst, typicallydisposed in a layer at each membrane/fluid distribution layer interface,to induce the desired electrochemical reaction in the fuel cell. Theelectrodes thus formed are electrically coupled to provide a path forconducting electrons between the electrodes through an external load.

At the anode, the fluid fuel stream moves through the porous portion ofthe anode fluid distribution layer and is oxidized at the anodeelectrocatalyst. At the cathode, the fluid oxidant stream moves throughthe porous portion of the cathode fluid distribution layer and isreduced at the cathode electrocatalyst.

In fuel cells employing hydrogen as the fuel and oxygen as the oxidant,the catalyzed reaction at the anode produces hydrogen cations (protons)from the fuel supply. The ion exchange membrane facilitates themigration of protons from the anode to the cathode. In addition toconducting protons, the membrane isolates the hydrogen-containing fuelstream from the oxygen-containing oxidant stream. At the cathodeelectrocatalyst layer, oxygen reacts with the protons that have crossedthe membrane to form water as the reaction product. The anode andcathode reactions in hydrogen/oxygen fuel cells are shown in thefollowing equations:Anode reaction: H₂→2H⁺+2e⁻Cathode reaction: 1/2O₂+2H⁺+2e⁻→H₂O

In fuel cells employing methanol as the fuel supplied to the anode(so-called “direct methanol” fuel cells) and an oxygen-containingstream, such as air (or substantially pure oxygen) as the oxidantsupplied to the cathode, the methanol is oxidized at the anode toproduce protons and carbon dioxide. Typically, the methanol is suppliedto the anode as an aqueous solution or as a vapor. The protons migratethrough the ion exchange membrane from the anode to the cathode, and atthe cathode electrocatalyst layer, oxygen reacts with the protons toform water. The anode and cathode reactions in this type of directmethanol fuel cell are shown in the following equations:

 Anode reaction: CH₃OH+H₂O→6H⁺+CO₂+6e⁻Cathode reaction: 3/2O₂+6H⁺+6e⁻→3H₂O

In fuel cells, the MEA is typically interposed between two separatorplates or fluid flow field plates (anode and cathode plates). The platestypically act as current collectors, provide support to the MEA, andprevent mixing of the fuel and oxidant streams in adjacent fuel cells,thus, they are typically electrically conductive and substantially fluidimpermeable. Fluid flow field plates typically have channels, grooves orpassages formed therein to provide means for access of the fuel andoxidant streams to the surfaces of the porous anode and cathode layers,respectively.

Two or more fuel cells can be connected together, generally in seriesbut sometimes in parallel, to increase the overall power output of theassembly. In series arrangements, one side of a given plate serves as ananode plate for one cell and the other side of the plate can serve asthe cathode plate for the adjacent cell, hence the plates are sometimesreferred to as bipolar plates. Such a series connected multiple fuelcell arrangement is referred to as a fuel cell stack. The stacktypically includes manifolds and inlet ports for directing the fuel andthe oxidant to the anode and cathode fluid distribution layers,respectively. The stack also usually includes a manifold and inlet portfor directing the coolant fluid to interior channels within the stack.The stack also generally includes exhaust manifolds and outlet ports forexpelling the unreacted fuel and oxidant streams, as well as an exhaustmanifold and outlet port for the coolant fluid exiting the stack.

The fluid distribution layer in fuel cells has several functions,typically including:

-   -   (1) to provide access of the fluid reactants to the        electrocatalyst;    -   (2) to provide a pathway for removal of fluid reaction product        (for example, water in hydrogen/oxygen fuel cells and water and        carbon monoxide in direct methanol fuel cells);    -   (3) to serve as an electronic conductor between the        electrocatalyst layer and the adjacent separator or flow field        plate;    -   (4) to serve as a thermal conductor between the electrocatalyst        layer and the adjacent separator or flow field plate;    -   (5) to provide mechanical support for the electrocatalyst layer;    -   (6) to provide mechanical support and dimensional stability for        the ion exchange membrane.

The fluid distribution layer is electrically conductive across at leasta portion of its surface area to provide an electrically conductive pathbetween the electrocatalyst reactive sites and the current collectors.Materials that have been employed in fluid distribution layers in solidpolymer fuel cells include:

-   -   (a) carbon fiber paper;    -   (b) woven and non-woven carbon fabric—optionally filled with        electrically conductive filler such as carbon particles and a        binder;    -   (c) metal mesh or gauze—optionally filled with electrically        conductive filler such as carbon particles and a binder;    -   (d) polymeric mesh or gauze, such as polytetrafluoroethylene        mesh, rendered electrically conductive, for example, by filling        with electrically conductive filler such as carbon particles and        a binder.    -   (e) microporous polymeric film, such as microporous        polytetrafluoroethylene, rendered electrically conductive, for        example, by filling with electrically conductive filler such as        carbon particles and a binder.

Thus, fluid distribution layers typically comprise preformed sheetmaterials that are electrically conductive and fluid permeable in theregion corresponding to the electrochemically active region of the fuelcell.

Conventional methods of sealing around MEAs within fuel cells includeframing the MEA with a resilient fluid impermeable gasket, placingpreformed seal assemblies in channels in the fluid distribution layerand/or separator plate, or molding seal assemblies within the fluiddistribution layer or separator plate, circumscribing theelectrochemical active region and any fluid manifold openings. Examplesof such conventional methods are disclosed in U.S. Pat. Nos. 5,176,966and 5,284,718. Disadvantages of these conventional approaches includedifficulty in assembling the sealing mechanism, difficulty in supportingnarrow seal assemblies within the fluid distribution layer, localizedand uneven mechanical stresses applied to the membrane and sealassemblies, and seal deformation and degradation over the lifetime ofthe fuel cell stack.

Such gaskets and seals, which are separate components introduced inadditional processing or assembly steps, add complexity and expense tothe manufacture of fuel cell stacks.

SUMMARY OF THE INVENTION

A fuel cell fluid distribution layer is provided. In one embodiment, thefluid distribution layer comprises perforated graphite foil. The fluiddistribution layer can have:

-   -   one or more reactant flow field channels formed in one or both        major surfaces;    -   one or more manifold openings;    -   conductive filler on one or both major surfaces;    -   conductive filler at least partially filling some or all        perforations; and/or    -   an electrocatalyst one or both major surfaces.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded sectional view of a conventional (prior art) solidpolymer fuel cell showing an MEA interposed between two flow fieldplates.

FIG. 2A is an exploded sectional view, in the direction of arrows A—A inFIG. 2B, of a fuel cell that includes a pair of fluid flow field platesand a pair of fluid distribution layers with integral sealingcapability. The fluid distribution layers include a polymeric mesh sheetmaterial that has been melt-bonded in the sealing region. FIG. 2B is anexploded isometric view of a portion of the fuel cell of FIG. 2A.

FIG. 3A is an exploded sectional view, in the direction of arrows B—B inFIG. 3B, of a fuel cell which includes a pair of fluid flow field platesand a pair of fluid distribution layers with integral sealingcapability. The fluid distribution layers include a substantially fluidimpermeable sheet material having plurality of perforations formed inthe electrochemically active region thereof. FIG. 3B is an explodedisometric view of a portion of the fuel cell of FIG. 3A.

FIG. 4A is an exploded sectional view, in the direction of arrows C—C inFIG. 4B, of a fuel cell which includes a pair of separator plates and apair of fluid distribution layers with integral sealing capability. Thefluid distribution layers include a substantially fluid impermeablesheet material having plurality of perforations in the electrochemicallyactive region thereof, and fluid flow channels formed in a major surfacethereof. FIG. 4B is an exploded isometric view of a portion of the fuelcell of FIG. 4A.

FIG. 5 is a schematic diagram illustrating a fabrication processsuitable for manufacture of fuel cells with fluid distribution layerswith integral sealing capability.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)

FIG. 1 illustrates a typical (prior art) solid polymer fuel cell 10.Fuel cell 10 includes an MEA 12 including an ion exchange membrane 14interposed between two electrodes, namely, an anode 16 and a cathode 17.Anode 16 includes a porous electrically conductive fluid distributionlayer 18. A thin layer of electrocatalyst 20 is disposed at theinterface with the membrane 14, thereby defining an electrochemicallyactive region of fluid distribution layer 18. Cathode 17 includes aporous electrically conductive fluid distribution layer 19. A thin layerof electrocatalyst 21 is disposed at the interface with the membrane 14,thereby defining an electrochemically active region of fluiddistribution layer 19. The MEA is interposed between anode flow fieldplate 22 and cathode flow field plate 24. Anode flow field plate 22 hasat least one fuel flow channel 23 formed in its surface facing the anodefluid distribution layer 18. Cathode flow field plate 24 has at leastone oxidant flow channel 25 formed in its surface facing the cathodefluid distribution layer 19. When assembled against the cooperatingsurfaces of the fluid distribution layers 18 and 19, channels 23 and 25form reactant flow field passages for the fuel and oxidant,respectively. Membrane electrode assembly 12 also includes preformedgaskets 26 placed within channels 27, which extend through the thicknessof the fluid distribution layers 18 and 19. When the fuel cell 10 isassembled and compressed, by urging plates 22 and 24 towards each other,the gaskets 26 cooperate with the plates 22, 24 and the membrane 14 toform a seal circumscribing the electrochemically active region of eachfluid distribution layer 18, 19.

FIG. 2A is an exploded sectional view of a fuel cell 210, a portion ofwhich is shown in FIG. 2B in an exploded isometric view. Fuel cell 210includes a membrane electrode assembly 212, which includes an ionexchange membrane 214 interposed between a pair of fluid distributionlayers 218 and 219. A quantity of electrocatalyst is disposed in a layer220, 221 at the interface between each fluid distribution layer 218, 219and membrane 214 in the electrochemically active region 230 of the fluiddistribution layers 218, 219. The catalyst can be applied to themembrane or to the fluid distribution layer. The MEA 212 is interposedbetween a pair of flow field plates 222 and 224. Each plate 222, 224 hasan open-faced channel 223, 225 formed in its surface facing thecorresponding fluid distribution layer 218, 219, respectively, andtraversing a portion of each plate that superposes the electrochemicallyactive region 230. When assembled against the cooperating surfaces ofthe fluid distribution layers 218 and 219, channels 223 and 225 formreactant flow field passages for the fuel and oxidant, respectively.

Fluid distribution layers 218, 219 each have a sealing region 240. Inthe illustrated embodiment, ion exchange membrane 214 superposes sealingregion 240 and can be melt-bonded thereto. In the electrochemicallyactive region 230, the fluid distribution layers 218, 219 areelectrically conductive and fluid permeable, to permit the passage ofreactant fluid between the two major planar surfaces thereof to accessthe electrocatalyst layer 220, 221 respectively. In the embodimentillustrated in FIGS. 2A and 2B, fluid distribution layers include anelectrically insulating preformed polymeric mesh sheet material 250extending into each of the active and sealing regions 230, 240,respectively. The fluid distribution layer is rendered electricallyconductive in the active region 230, for example, it can contain anelectrically conductive filler, at least in the region 230. Polymericmesh sheet material 250 is melt-bonded at locations 245 in the sealingregion 240 thereby rendering the fluid distribution layers substantiallyfluid impermeable in a direction parallel to their major planarsurfaces. Further, polymeric mesh sheet material 250 is melt-bonded toion exchange membrane 214 at locations 245 thereby also effecting a sealbetween fluid distribution layers 218, 219 and membrane 214. Themelt-bonding within mesh sheet material 250 at locations 245 and themelt-bonding of mesh sheet material 250 to membrane 214 can desirably beaccomplished in one step. A suitable melt-bond can be obtained using aconventional technique appropriate for the joining of thermoplasticsand/or other polymeric materials generally, such as heat bonding orultrasonic welding. Where appropriate, solvent bonding can also beemployed (for example, where a solvent is used to dissolve the polymericsheet material after which the solvent is removed, leaving a melt-bondedpolymeric seal). Seals between the melt-bonded membrane electrodeassembly 212 and plates 222, 224 are effected by compression of thefluid distribution layers 218, 219 in the sealing region 240 betweenplates 222, 224. Thus, complete sealing around the periphery of theactive region 230, is accomplished partly by melt-bonding of thethermoplastic and/or other polymeric material, and partly bycompression. Suitable mesh materials include expanded polyolefinmaterials, such as expanded polypropylene or polyethylene.

As shown in FIG. 2B, each of membrane 214, fluid distribution layer 219,reactant flow field plate 224, has a plurality of openings 260 formedtherein, which align when assembled to form manifolds for directinginlet and outlet fluid streams through fuel cell 210. For example,oxidant fluid flow field channel 225 extends between oxidant inletmanifold opening 260 a and oxidant outlet manifold 260 b formed in plate224. The fluid manifold openings 260 in fluid distribution layers 218,219 are formed in sealing region 240. Openings, 260, need notnecessarily be formed in the mesh material of the fluid distributionlayer, as the fluid passing through the manifold can generally readilypass through the mesh material. Melt-bonded locations 245 appear betweenactive region 230 and openings 260.

In FIG. 2A, other polymeric preformed sheets (for example, suitablemicroporous films) can be employed in the fluid distribution layers 218,219 instead of the expanded polymeric mesh sheet material 250. Further,in principle, polymeric particulate filled fluid distribution layersmight also be sealed in this way. Thus, polymeric particulates (forexample, plastic fibers) dispersed throughout the fluid distributionlayer can be employed instead of a mesh.

In the embodiment of FIG. 2A, melt-bonding of the fluid distributionlayers to the membrane is preferred since this provides a seal at thefluid distribution layer/membrane interface and can result in simpleroverall manufacture of an MEA. However, this interfacial seal caninstead be effected by compression where desired (for instance if themembrane and polymeric material in the fluid distribution layer are notsuitably compatible).

FIG. 3A is an exploded sectional view of a fuel cell 310, a portion ofwhich is shown in FIG. 3B in an exploded isometric view. Again, fuelcell 310 includes a membrane electrode assembly 312, including an ionexchange membrane 314 interposed between a pair of fluid distributionlayers 318 and 319, with a quantity of electrocatalyst disposed in alayer 320, 321 at the interface between each fluid distribution layer318, 319 and membrane 314 in the electrochemically active region 330 ofthe fluid distribution layers 318, 319. The MEA 312 is interposedbetween a pair of flow field plates 322 and 324, each plate having anopen-faced channel 323, 325 formed in its surface facing thecorresponding fluid distribution layer 318, 319, respectively, asdescribed for FIGS. 2A and 2B above.

Fluid distribution layers 318, 319 each have a sealing region 340. Inthe illustrated embodiment, ion exchange membrane 314 superposes only aportion of the sealing region 340 circumscribing the active region 330.The membrane 314 does not superpose entire sealing region 340. In theelectrochemically active region 330, the fluid distribution layers 318,319 are electrically conductive and fluid permeable. In the embodimentillustrated in FIGS. 3A and 3B, fluid distribution layers includesubstantially fluid impermeable sheet material 350 extending into eachof the active and sealing regions 330, 340, respectively. The sheetmaterial 350 is perforated at least in the electrochemically activeregion, rendering it fluid permeable, to permit the passage of reactantfluid between the two major planar surfaces thereof for access to theelectrocatalyst layer 320, 321 respectively.

In the illustrated embodiment, the substantially fluid impermeable sheetmaterial 350 is formed from an electrically insulating polymericmaterial such as polytetrafluoroethylene or an elastomer such asSantoprene® brand rubber available through Monsanto Company. As thesheet material 350 is electrically insulating, the fluid distributionlayer is rendered electrically conductive in the active region 330. Forexample, the perforations 352 can contain an electrically conductivefiller 354. Compression of sheet material 350 in fluid distributionlayers 318, 319 between membrane 314 and plates 322, 324 respectively,renders the fluid distribution layers substantially fluid impermeable ina direction parallel to their major planar surfaces in the sealingregion 340, by virtue of the fluid impermeability of the sheet material350 which extends into the sealing region 340.

As shown in FIG. 3B, each of the fluid distribution layers 318, 319, andreactant flow field plates 322, 324, has a plurality of openings 360formed therein, which align when assembled to form manifolds fordirecting inlet and outlet fluid streams through fuel cell 310, asdescribed above. For example, oxidant fluid flow field channel 325extends between oxidant inlet manifold opening 360 a and oxidant outletmanifold 360 b formed in plate 324. The two fluid distribution layers318, 319 and the reactant flow field plates 322, 324 cooperate to form aseal circumscribing the manifold openings 360. Whereas sealing aroundthe periphery of the active region 340 in the embodiment of FIGS. 3A and3B, is accomplished by utilizing the intrinsic sealing capability of thesheet material 350 when it is interposed and compressed between theplates 322, 324 and the membrane 314. If the fluid distribution layers318, 319 are electrically conductive in sealing region 340 and membrane314 does not superpose the entire sealing region 340, an electricalinsulator would need to be interposed between layers 318, 319 to preventshort circuiting.

FIG. 4A is an exploded sectional view of a fuel cell 410, a portion ofwhich is shown in FIG. 4B in an exploded isometric view. Fuel cell 410is very similar to fuel cell 310 of FIGS. 3A and 3B, again including amembrane electrode assembly 412, including an ion exchange membrane 414interposed between a pair of fluid distribution layers 418, 419, withelectrocatalyst-containing layers 420, 421 defining theelectrochemically active region 430 of the fluid distribution layers418, 419. The MEA 412 is interposed between a pair of separator plates422 and 424.

Fluid distribution layers 418, 419 each have a sealing region 440. Inthe illustrated embodiment, ion exchange membrane 414 superposes sealingregion 440. In the electrochemically active region 430, the fluiddistribution layers 418, 419 are electrically conductive and fluidpermeable. In the embodiment illustrated in FIGS. 4A and 4B, fluiddistribution layers include substantially fluid impermeable sheetmaterial 450 extending into each of the active and sealing regions 430,440, respectively. The sheet material 450 is perforated at least in theelectrochemically active region, rendering it fluid permeable, to permitthe passage of reactant fluid between the two major planar surfacesthereof for access to the electrocatalyst layer 420, 421 respectively.

In the illustrated embodiment, the substantially fluid impermeable sheetmaterial 450 is formed from an electrically conductive material such asgraphite foil, carbon resin or a metal. The perforations 452 preferablycontain an electrically conductive filler 454.

In the illustrated embodiment, each fluid distribution layer 418, 419has an open-faced channel 423, 425 formed in its surface facing thecorresponding separator plate 422, 424, respectively, and traversing theelectrochemically active region 430. When assembled against thecooperating surfaces of the plates 422 and 424, channels 423 and 425form reactant flow field passages for the fuel and oxidant,respectively.

An embodiment such as the one illustrated in FIGS. 4A and 4B integratesseveral functions including sealing, fluid distribution includingprovision of a flow field, and current collection, in a single layer orcomponent.

Compression of sheet material 450 in fluid distribution layers 418, 419between membrane 414 and plates 422, 424, respectively, renders thefluid distribution layers 418, 419 substantially fluid impermeable in adirection parallel to their major planar surfaces in the sealing region440, by virtue of the fluid impermeability of the sheet material 450which extends into the sealing region 440.

As shown in FIG. 4B, each of the membrane 414, fluid distribution layers418, 419, reactant flow field plates 422, 424, has a plurality ofopenings 460 formed therein, which align when assembled to formmanifolds for directing inlet and outlet fluid streams through fuel cell410, as described above.

A wide variety of fabrication processes can be used to manufacture andassemble fuel cells of the present design. The design is believed to besuited for high throughput manufacturing processes. FIG. 5 is aschematic diagram illustrating a possible fabrication approach for afuel cell similar to that illustrated in FIGS. 4A and 4B. FIG. 5 showsschematically the preparation of a fluid distribution layers 518, andthe consolidation of two such layers 518, 519 with a catalyzed membrane514 and a separator layer 522, in a reel-to-reel type process. Forexample, fluid distribution layers 518 are formed by selectivelyperforating a substantially fluid impermeable preformed sheet material550 in the active region, in a perforation step 580. The sheet materialcould, for example, be graphite foil. In a subsequent step 585, theperforations are at least partially filled with an electricallyconductive filler, such as carbon particles and a polymeric binder. Alayer of conductive filler can also be deposited on one or both majorsurfaces of the perforated sheet material 550. Reactant flow fieldchannels 523 can be formed in one or both major surfaces of the fluiddistribution layer in step 590, for example, by embossing. A multi-layerfuel cell assembly 510 can be formed by bringing together, in aconsolidation step 595, two fluid distribution layers 518, 519, with anion exchange membrane 514, and a substantially fluid impermeableseparator layer 522. The consolidation step could include a thermallamination and/or pressure bonding process. The ion exchange membrane514 has a electrocatalyst-containing layer on a portion of both of itsmajor surfaces, defining the electrochemically active region.Alternatively, the electrocatalyst could be deposited on the fluiddistribution layers 518, 519 prior to consolidation step 595. Theassemblies can then optionally be cut into single cell units, andlayered to form a fuel cell stack, wherein separator layers 522 willserve as bipolar plates. FIG. 5 illustrates how the present fuel celldesign with fluid distribution layers with integral seal capability, issuitable for fabrication via a continuous, high throughput manufacturingprocess, with little material wastage and few individual components andprocessing steps.

The practical advantages of the present fuel cell with a fluiddistribution layer having integral sealing capability is the combinationof the sealing and fluid distribution functions into one fluiddistribution layer, thereby reducing cost, simplifying the components,and improving their reliability. This approach reduces or eliminates theneed for separate sealing components in a fuel cell assembly. A furtheradvantage with the non-porous sheet material embodiments is the abilityto control the electrochemical reaction rate by varying the number offilled holes across the active region and thereby controlling reactantaccess to the electrocatalyst.

In all of the above embodiments, the fuel cell can include additionallayers of material interposed between those shown, or the componentsshown can be multi-layer structures. Such additional layers may or maynot superpose both the electrochemically active region and the sealingregion. The separator plates can optionally have raised sealing ridgesprojecting from the major surfaces thereof in the sealing region. In afuel cell assembly under compression, the sealing ridges will compressthe fluid distribution layer.

Those in the art will appreciate that the general principles disclosedin the preceding can be expected to apply to both gas and liquid feedfuel cells, for example, gaseous hydrogen/air solid polymer fuel cellsand liquid methanol/air or “direct methanol” solid polymer fuel cells.However, it is expected that fewer polymers will be suitable for use inthe latter since a suitable polymer would have to be compatible withliquid methanol.

While particular elements, embodiments and applications of the presentinvention have been shown and described, it will be understood, ofcourse, that the invention is not limited thereto since modificationscan be made by those skilled in the art, particularly in light of theforegoing teachings. It is therefore contemplated by the appended claimsto cover such modifications as incorporate those features that comewithin the scope of the invention.

1. A fuel cell fluid distribution layer comprising perforated graphitefoil and a conductive filler at least partially filing at least aportion of the perforations.
 2. The fluid distribution layer of claim 1,wherein a reactant flow field channel is formed in a major surfacethereof.
 3. The fluid distribution layer of claim 1, wherein a manifoldopening is formed therein.
 4. The fluid distribution layer of claim 1,further comprising a conductive filler disposed on at least one majorsurface thereof.
 5. The fluid distribution layer of claim 4 wherein theconductive filler at least partially filling at least a portion of theperforations and the conductive filler disposed on at least one majorsurface have the same composition.
 6. The fluid distribution layer ofclaim 1, further comprising an electrocatalyst disposed on at least onemajor surface thereof.
 7. The fluid distribution layer of claim 1wherein the graphite foil comprises a perforated active region and afluid impermeable sealing region.
 8. A fuel cell comprising a fluiddistribution layer comprising perforated graphite foil.
 9. The fuel cellof claim 8, wherein the fluid distribution layer has a reactant flowfield channel formed in a major surface thereof.
 10. The fuel cell ofclaim 8, wherein the fluid distribution layer has a manifold openingformed therein.
 11. The fuel cell of claim 8, wherein the fluiddistribution layer further comprises a conductive filler at leastpartially filling at least a portion of the perforations.
 12. The fuelcell of claim 11, wherein the fluid distribution layer further comprisesa conductive filler disposed on at least one major surface thereof. 13.The fuel cell of claim 12, wherein the conductive filler at leastpartially filling at least a portion of the perforations and theconductive filler disposed on at least one major surface have the samecomposition.
 14. The fuel cell of claim 8, wherein the fluiddistribution layer has an electrocatalyst disposed on at least one majorsurface thereof.
 15. The fuel cell of claim 8 wherein the graphite foilcomprises a perforated active region and a fluid impermeable sealingregion.
 16. A method of making a fuel cell, the method comprisingincorporating a fluid distribution layer in the fuel cell, wherein thefluid distribution layer comprises perforated graphite foil.
 17. Themethod of claim 16, further comprising forming a reactant flow fieldchannel in a major surface of the fluid distribution layer.
 18. Themethod of claim 16, further comprising forming a manifold opening formedin the fluid distribution layer.
 19. The method of claim 16, furthercomprising at least partially filling at least a portion of the fluiddistribution layer perforations with a conductive filler.
 20. The methodof claim 19, further comprising disposing a conductive filler on atleast one major surface of the fluid distribution layer.
 21. The methodof claim 20, wherein the conductive filler at least partially filling atleast a portion of the perforations and the conductive filler disposedon at least one major surface conductive have the same composition. 22.The method of claim 16, further comprising disposing an electrocatalyston at least one major surface of the fluid distribution layer.
 23. Themethod of claim 16, wherein the graphite foil comprises a perforatedactive region and a fluid impermeable sealing region.